Process and related device for removing by-product on semiconductor processing chamber sidewalls

ABSTRACT

In some embodiments, a method for cleaning a processing chamber is provided. The method may be performed by introducing a processing gas into a processing chamber that has a by-product disposed along sidewalls of the processing chamber. A plasma is generated from the processing gas using a radio frequency signal. A lower electrode is connected to a first electric potential. Concurrently, a bias voltage having a second electric potential is applied to a sidewall electrode to induce ion bombardment of the by-product, in which the second electric potential has a larger magnitude than the first electric potential. The processing gas is evacuated from the processing chamber.

REFERENCE TO RELATED APPLICATION

This Application is a Continuation of U.S. application Ser. No.15/927,308, filed on Mar. 21, 2018, which claims the benefit of U.S.Provisional Application No. 62/565,673, filed on Sep. 29, 2017. Thecontents of the above referenced Patent Applications are herebyincorporated by reference in their entirety.

BACKGROUND

Semiconductor processing equipment, such as plasma-enhanced chemicalvapor deposition (PE-CVD) systems, plasma etching systems, andsputtering systems, are used extensively throughout the production ofmodern day electronic devices. This semiconductor processing equipmentmay contain a processing chamber that helps contain the often reactiveprocesses performed by this equipment. Due to these processes,by-products may form on a sidewall of the processing chamber resultingin decreased performance and/or contamination of the equipment, whichmay result in a decrease in the yield of electronic devices. In anattempt to maintain equipment efficiency and the yield of electronicdevices, a cleaning process is often performed to remove the by-productbuildup on the sidewall of the processing chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a view of some embodiments of a semiconductorprocessing system capable of implementing a method of the presentdisclosure for removing by-product that has accumulated on sidewalls ofa processing chamber.

FIGS. 2A-2B illustrates a series of views of more detailed embodimentsof a semiconductor processing system capable of implementing a method ofthe present disclosure for removing by-product that has accumulated onsidewalls of a processing chamber.

FIGS. 3A-3G illustrate a series of views of some embodiments of a methodfor removing by-product that has accumulated on sidewalls of aprocessing chamber.

FIGS. 4A-4B illustrate a series of views of some more embodiments of amethod for removing by-product that has accumulated on sidewalls of aprocessing chamber.

FIG. 5 illustrates a flowchart of some embodiments of the method forremoving by-product that has accumulated on sidewalls of a processingchamber.

DETAILED DESCRIPTION

The present disclosure will now be described with reference to thedrawings wherein like reference numerals are used to refer to likeelements throughout, and wherein the illustrated structures are notnecessarily drawn to scale. It will be appreciated that this detaileddescription and the corresponding figures do not limit the scope of thepresent disclosure in any way, and that the detailed description andfigures merely provide a few examples to illustrate some ways in whichthe inventive concepts can manifest themselves.

The present disclosure provides many different embodiments, or examples,for implementing different features of this disclosure. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Integrated circuit (IC) technologies are constantly being improved.These improvements typically involve scaling down of geometries toachieve lower fabrication costs, higher device integration density,higher speeds, and better performance. Due to device scaling, thenegative effects of sidewall contamination (e.g., contamination of asubstrate resulting from unwanted containments being dislodged from asidewall of a processing chamber and accumulating on a surface of thesubstrate) occurring in a processing chamber are magnified.

For example, a workpiece may be loaded into a processing chamber of aplasma etching system. The workpiece may comprise a patternedphotoresist layer disposed over an inert metal layer (e.g., silver,copper, etc.). The plasma processing system generates a plasma insidethe processing chamber to selectively etch the inert metal layer. Duringthis process, non-volatile by-product is generated and often accumulateson sidewalls of the processing chamber. As the workpiece (or subsequentworkpieces) undergoes processing in the processing chamber, the plasmawill break some of the bonds of the non-volatile by-product disposed onthe processing chamber sidewalls causing atoms of the non-volatileby-product to be dislodged from the sidewall. Accordingly, atoms of thenon-volatile by-product may accumulate as contaminants on the workpiecedisposed inside the processing chamber. The accumulation of non-volatileby-products on the workpiece may result in an improperly functioningintegrated circuit on the faulty workpiece. Current waferless auto-clean(WAC) processes are unable to effectively remove this non-volatileby-product from the processing chamber sidewalls due to lack of physicalbombardment of the non-volatile by-products. Therefore, a method (andrelated system) for cleaning a processing chamber that effectivelyremoves non-volatile by-product from processing chamber sidewalls wouldimprove the reliability and cost of ICs by increasing the efficiency ofsemiconductor processing equipment.

In some embodiments, the present disclosure relates to a method (andrelated system) for cleaning a processing chamber that effectivelyremoves non-volatile by-product from processing chamber sidewalls. Themethod comprises performing an etching process on a workpiece within aprocessing chamber. During the etching process, by-products from theworkpiece may be dislodged from the workpiece and adhere to the sidewallof the processing chamber. After the etching process is complete, theworkpiece is removed from the processing chamber. After the workpiece isremoved from the processing chamber, a processing gas is introduced intothe processing chamber and a plasma is generated from the processinggas. Concurrently, a bias voltage is applied to a sidewall electrode toinduce ion bombardment of the by-product disposed on the sidewall of theprocessing chamber. After the by-product has been effectively bombarded,the processing gas and the by-product can be evacuated from theprocessing chamber. By physically bombarding the by-product, theby-product can be effectively removed from the sidewalls of theprocessing chamber and evacuated along with the evacuation of theprocessing gas. Accordingly, because the improved method alters thetypical processing chamber cleaning process by applying a bias voltageto a sidewall electrode to induce ion bombardment, the improved methodmay increase the reliability of ICs and lower the cost of ICs byincreasing the efficiency of semiconductor processing equipment.

With reference to FIG. 1, a view of some embodiments of a semiconductorprocessing system 100 capable of implementing a method of the presentdisclosure for removing by-product that has accumulated on sidewalls ofa processing chamber is provided.

The semiconductor processing system 100 comprises a processing chamber102 having a first processing chamber sidewall 104 and a secondprocessing chamber sidewall 106. The processing chamber 102 may be, forexample, a plasma-enhanced chemical vapor deposition (PE-CVD) chamber.The processing chamber sidewalls 104/106 comprise a conductive material.In some embodiments, the processing chamber 102 may comprise adielectric layer disposed on sidewalls of the processing chamber 102that separates an inner chamber from an outer housing of the processingchamber 102.

A lower electrode 108 is disposed within the processing chamber 102. Insome embodiments, an electrostatic chuck 110 is also disposed within theprocessing chamber 102. In some embodiments, the electrostatic chuck 110comprises the lower electrode 108. In other embodiments, theelectrostatic chuck 110 comprises the lower electrode 108 and anelectrostatic chuck electrode (not shown). Further, the electrostaticchuck 110 is configured to hold a workpiece 114 throughout variousstages of processing the workpiece 114. In some embodiments, theworkpiece 114 comprises a metal layer 118 disposed over a substrate 116and a photoresist layer 120 disposed over the metal layer 118. In someembodiments, the metal layer 118 may be an inert metal, for example,copper, silver, gold, or some other inert metal. Moreover, anelectrostatic chuck pedestal 112 may support the lower electrode 108 andthe electrostatic chuck 110. In some embodiments, the electrostaticchuck pedestal 112 comprises an electrical insulating materialconfigured to insulate the electrostatic chuck 110 and the lowerelectrode 108 from the processing chamber sidewalls.

The processing chamber 102 further comprises a processing gas inlet 122and a processing chamber gas outlet 124. In some embodiments, theprocessing gas inlet 122 comprises a valve to control the flow of aprocessing gas 126 into the processing chamber 102, and the processingchamber gas outlet 124 comprises a valve to control the flow of theprocessing gas 126 out of the processing chamber. Further, in someembodiments, the processing gas inlet 122 and the processing chamber gasoutlet 124 allow a pressure inside the processing chamber 102 to becontrolled. In some embodiments, the processing chamber gas outlet 124may be used in conjunction with a vacuum pump to pump the processingchamber 102 down to a vacuum. In other embodiments, the semiconductorprocessing system 100 comprises a vacuum pump coupled to a separateorifice into the processing chamber 102 that allows the processingchamber to be pumped down to a vacuum.

The semiconductor processing system 100 also comprises a plasma source125 configured to provide a plasma within the processing chamber 102. Insome embodiments the plasma source 125 may comprise a first radiofrequency (RF) power generator 127 coupled to an RF antenna 121 that iselectrically insulated from the processing chamber sidewalls 104/106 byRF antenna insulators 123. In some embodiments, the RF antenna 121 maycomprise two metal electrodes separated by a small distance and may bedisposed within the sidewall of the processing chamber 102. This type ofRF antenna 121 may be used in a capacitively coupled plasma (CCP)source. In other embodiments, the RF antenna 121 may have a coil-likeshape and may be disposed outside the sidewalls of the processingchamber 102. This type of RF antenna 121 may be used in an inductivelycoupled plasma (ICP) source. In yet other embodiments, the RF antenna121 may be a sidewall of the processing chamber 102. The first RF powergenerator 127 is configured to apply a RF signal having an electricpotential to the RF antenna 121 to form a plasma 129 from the processinggas 126 inside the processing chamber 102. In some embodiments, thefirst RF power generator 127 operates in a power range between about 200W and about 3000 W, and generates an RF signal with a frequency betweenabout 13.56 MHz and about 60 MHz. In some embodiments, a matchingnetwork is disposed between the first RF power generator 127 and the RFantenna 121. In other embodiments, the plasma source 125 may comprise aremote plasma source configured to generate a plasma within an upstreamplasma generation chamber and to subsequently provide the plasma to theprocessing chamber 102.

Further, the semiconductor processing system 100 comprises a lowerelectrode RF power generator 128 coupled to the lower electrode 108. Thelower electrode RF power generator 128 comprises a switching elementconfigured to switch between a first terminal having a first electricpotential (e.g., about negative 600 V) and a second terminal having asecond electric potential (e.g., about 0 V). In some embodiments, thefirst terminal is also coupled to an RF signal generator. The lowerelectrode RF power generator is configured to provide a RF signal to thelower electrode 108 to increase the efficiency of the semiconductorprocessing system 100 (e.g., by maintaining control over a plasma sheathof the plasma). In some embodiments, the lower electrode RF powergenerator 128 operates in a power range between about 200 W and about3000 W, and generates an RF signal with a frequency between about 400kHZ and about 13.56 MHz.

In some embodiments, the lower electrode RF power generator 128 alsoprovides signals to an electrostatic chuck electrode (not shown)disposed within the electrostatic chuck 110. In other embodiments, aseparate electrostatic chuck power generator 130 is configured to applya voltage to the electrostatic chuck electrode (not shown). In yet otherembodiments, a second RF power generator 132 comprises the electrostaticchuck power generator 130 and the lower electrode RF power generator128.

Moreover, the semiconductor processing system 100 comprises a firstsidewall voltage generator 134 coupled to a first sidewall electrode136, and a second sidewall voltage generator 138 coupled to a secondsidewall electrode 140. In some embodiments, the first sidewall voltagegenerate 134 and the second sidewall voltage generate 138 may be a samevoltage generator. The first sidewall electrode 136 and the secondsidewall electrode 140 comprise an electrical conducting material. Insome embodiments, the first sidewall electrode 136 is the firstprocessing chamber sidewall 104 and the second sidewall electrode 140 isthe second processing chamber sidewall 106. In other embodiments, thefirst sidewall electrode 136 is arranged behind the first processingchamber sidewall 104 and the second sidewall electrode 140 is arrangedbehind the second processing chamber sidewall 106. The first sidewallvoltage generator 134 and the second sidewall voltage generator 138 areconfigured to apply a voltage to the first processing chamber sidewall104 and the second processing chamber sidewall 106, respectively. Insome embodiments, the first sidewall voltage generator 134 and thesecond sidewall voltage generator 138 may generate a negative AC biasvoltage.

By using the first sidewall voltage generator 134 and the secondsidewall voltage generator 138 to apply a voltage to the processingchamber sidewalls 104/106, a velocity at which gas particles within theprocessing chamber are attracted to the processing chamber sidewalls104/106 is increased. The increased velocity of the gas particles causesthe gas particles to bombard a by-product that has collected on theprocessing chamber sidewalls 104/106 with a sufficient energy todislodge the by-product from the processing chamber sidewalls 104/106.Once dislodged, the by-product can be evacuated from the processingchamber 102 through the processing chamber gas outlet 124, therebydecreasing contamination of subsequently processed substrates within theprocessing chamber 102.

With reference to FIG. 2, a series of views of some more detailedembodiments of a semiconductor processing system 100 capable ofimplementing a method of the present disclosure for removing by-productthat has accumulated on sidewalls of a processing chamber is provided.FIG. 2A illustrates a cross-sectional view of a more detailedembodiments of a semiconductor processing system capable of implementinga method of the present disclosure. FIG. 2B illustrates a top view of amore detailed embodiments of a semiconductor processing system capableof implementing a method of the present disclosure.

As illustrated by the views of FIGS. 2A-2B, both the first RF powergenerator 127 and the second RF power generator 132 may further comprisea switching element 204 and a RF signal generator 202. The switchingelement 204 of the first RF power generator 127 is disposed between theRF signal generator 202 and the RF antenna 121. In some embodiments, theswitching element 204 of the first RF power generator 127 is configuredto open and close a circuit connecting the RF signal generator 202 tothe RF antenna 121. In other embodiments, the switching element 204 ofthe first RF power generator 127 is configured to switch between a firstterminal connected to the RF signal generator 202 and a second terminalconnected to ground. The switching element 204 of the second RF powergenerator 132 is disposed between the RF signal generator 202 and thelower electrode 108. The lower electrode 108 is configured to receive afirst electric potential (e.g., about negative 600 volts (V)) and asecond electric potential (e.g., about 0 V). The switching element 204of the second RF power generator 132 is configured to switch between afirst terminal having a first electric potential (e.g., about negative600 V) and a second terminal having a second electric potential (e.g.,about 0 V). In some embodiments, the first terminal is also coupled toan RF signal generator 202.

The first processing chamber sidewall 104 may be a single continuouspiece of conductive material that has a cylindrical shape. In someembodiments, the first sidewall electrode 136 may be a single continuouspiece of conductive material having a cylindrical shape that surroundsthe first processing chamber sidewall 104. In some such embodiments, thefirst sidewall voltage generator 134 may be connected to the firstsidewall electrode 136 and configured to provide a voltage to the entirefirst sidewall electrode 136. In some alternative embodiments, aplurality of separate sidewall electrodes may surround the firstprocessing chamber sidewall 104. In some such embodiments, the separatesidewall electrodes may be coupled to different sidewall voltagegenerators (e.g., a first sidewall electrode may be coupled to a firstsidewall voltage generator and a second sidewall electrode may becoupled to a second sidewall voltage generator).

The first sidewall voltage generator 134 may comprise a switchingelement 204 configured to switch between a first terminal having a firstelectric potential (e.g., about negative 600 V) and a second terminalhaving a second electric potential (e.g., about 0 V). In someembodiments, the first terminal is also coupled to a DC bias voltagegenerator 206. In some embodiments, the DC bias voltage generator 206 isan AC bias voltage generator. The switching element 204 of the firstsidewall voltage generator 134 is disposed between the DC bias voltagegenerator 206 and a first sidewall electrode 136. The switching element204 is configured to switch between a first terminal connected to the DCbias voltage generator 206 and a second terminal connected to ground. Insome embodiments, the DC bias voltage generator 206 outputs a negativevoltage in a range of about 0.1 V to about 600 V. Although notillustrated in FIGS. 2A-2B, it will be appreciated that the secondsidewall voltage generator 138 may also comprises a switching element204 and a DC bias voltage generator 206

Moreover, in some embodiments, the semiconductor processing system 100comprises a heating element 208 to control the temperature inside theprocessing chamber 102. In some embodiments, the heating element 208 isthe processing chamber sidewalls 104/106.

With reference to FIGS. 3A-3G, a series of views of some embodiments ofa method for removing by-product that has accumulated on sidewalls of aprocessing chamber is provided.

As illustrated by FIG. 3A, a semiconductor processing system 100 isprovided. The semiconductor processing system 100 is pumping down apressure of a processing chamber 102 in preparation of performing anetching process on a workpiece 114. In some embodiments, the pressure inthe processing chamber 102 is controlled between 20 millitorr (mT) and100 mT. The workpiece 114 is arranged on an electrostatic chuck 110inside the processing chamber 102. In some embodiments, the workpiece114 comprises a photoresist layer 120 disposed over a metal layer 118that is disposed over a substrate 116.

Further, a valve of the processing chamber gas outlet 124 is open whilea valve of the processing gas inlet 122 is closed. A vacuum pump (notshown) may be connected downstream from the valve of the processingchamber gas outlet 124. The vacuum pump is configured to pump gas out ofthe processing chamber 102 to lower the pressure of the processingchamber 102. In some embodiments, the semiconductor processing system100 performs a purging step to remove unwanted gas molecules from theprocessing chamber 102 prior to pumping down the pressure of theprocessing chamber 102.

As the pressure of the processing chamber is pumped down, the switchingelement 204 disposed in the first RF power generator 127 may open acircuit between the RF antenna 121 and the RF signal generator 202 ofthe first RF power generator 127. Further, the switching element 204 ofthe second RF power generator 132 may connect the lower electrode 108 toground. Also, the switching element 204 of the first sidewall voltagegenerator 134 connects the first sidewall electrode 136 to ground. Inaddition, the switching element 204 of the second sidewall voltagegenerator 138 connects the second sidewall electrode 140 to ground.

As illustrated by FIG. 3B, the workpiece 114 is being etched by anetching plasma 302. In some embodiments, the etching plasma 302 isformed by flowing an etching gas 304 into the processing chamber 102 andapplying an RF signal to ignite the etching plasma 302. For example, thevalve of the processing gas inlet 122 may open and allow the etching gas304 to flow into the processing chamber 102. After the etching gas 304has flowed into the processing chamber 102, the switching element 204 ofthe first RF power generator 127 closes the circuit between the RFsignal generator 202 of the first RF power generator 127 and the RFantenna 121. In some embodiments, the first RF power generator 127operates in a power range between about 200 W and about 3000 W, andgenerates an RF signal with a frequency between about 13.56 MHz andabout 60 MHz. In some embodiments, the switching element 204 of thesecond RF power generator 132 also switches such that the RF signalgenerator 202 of the second RF power generator 132 is connected to thelower electrode 108. In some embodiments, the second RF power generator132 operates in a power range between about 200 W and about 3000 W, andgenerates an RF signal with a frequency between about 400k MHz and about13.56 MHz. Accordingly, the RF signals output by the RF antenna 121 andthe lower electrode 108 form the etching plasma 302, such that theworkpiece 114 can be etched.

In some embodiments, the etching plasma 302 etches away portions of ametal layer 118. As the etching plasma 302 etches away portions of themetal layer 118, a large amount of by-product 210 is generated andaccumulates on the processing chamber sidewalls 104/106. In someembodiments, the by-product 210 may be a non-volatile by-product, suchas, copper, silver, gold, or some other non-volatile by-product.Therefore, as the workpiece 114 (or subsequent workpieces) continues tobe etched, the etching plasma 302 will break some of the bonds of thenon-volatile by-product 310 disposed on the processing chamber sidewalls104/106 causing atoms of the non-volatile by-product to dislodged fromthe sidewalls. Accordingly, atoms of the non-volatile by-product 310 mayaccumulate as contaminants on the workpiece 114 disposed inside theprocessing chamber 102, which may result in a faulty workpiece.

As illustrated by FIG. 3C, the workpiece 114 has been removed from theprocessing chamber 102, and the pressure of the processing chamber 102is being pumped down in preparation of cleaning the non-volatileby-product 310 from the processing chamber sidewalls 104/106. In someembodiments, because the workpiece 114 is removed from the processingchamber 102 and the cleaning process is not a wet cleaning process, thecleaning process to remove the non-volatile by-product 310 from theprocessing chamber sidewalls 104/106 is referred to as a waferlessauto-clean (WAC) process. In some embodiments, the pressure of theprocessing chamber 102 is lowered to a range of about 40 millitorr (mT)to about 80 mT. In yet further embodiments, a heating element (notshown) heats the contents of the processing chamber 102 to a range ofabout 20° C. to about 80° C.

In some embodiments, during the pumping down phase of the cleaningprocess, the switching element 204 of the first RF power generator 127opens the circuit between the RF signal generator 202 of the first RFpower generator 127 and the RF antenna 121. Further, the switchingelement 204 of the second RF power generator 132 switches such that thelower electrode 108 is connected to ground. Moreover, the switchingelements 204 of the first sidewall voltage generator 134 and the secondsidewall voltage generator 138 connect the first sidewall electrode 136and the second sidewall electrode 140 to ground, respectively.

As illustrated by FIG. 3D, the non-volatile by-product 310 disposed onthe second processing chamber sidewall 106 is being cleaned from thesecond processing chamber sidewall 106. In some embodiments, thecleaning plasma 216 is formed inside the processing chamber 102 byflowing a processing gas 126 into the processing chamber 102 andigniting the plasma via RF signals. In some embodiments, the processinggas 126 may comprise, for example, oxygen, chlorine, boron, nitrogen,hydrogen, or a combination of the foregoing. For example, the valve ofthe processing gas inlet 122 may open and allow the processing gas 126to flow into the processing chamber 102. After the processing gas 126has flowed into the processing chamber 102, the switching element 204 ofthe first RF power generator 127 closes the circuit between the RFsignal generator 202 of the first RF power generator 127 and the RFantenna 121, such that the RF antenna 121 outputs RF signals.

Unlike during the etching process depicted in FIG. 3B, the switchingelement 204 of the second RF power generator 132 connects the lowerelectrode 108 to ground in order to protect the electrostatic chuck 110during the cleaning process. Rather, the switching element 204 of thesecond sidewall voltage generator 138 switches such that the secondsidewall electrode 140 is connected to the DC bias voltage generator 206of the second sidewall voltage generator 138. In some embodiments, thesecond sidewall electrode 140 may be connected to the DC bias voltagegenerator 206 for a time period in a range of about 400 seconds to about600 seconds. In other embodiments, the second sidewall electrode 140 maybe connected to the DC bias voltage generator 206 for a time period in arange of about 200 seconds to about 400 seconds. By connecting thesecond sidewall electrode 140 to the DC bias voltage generator 206 ofthe second sidewall voltage generator 138, the non-volatile by-product310 disposed on the second processing chamber sidewall 106 iseffectively cleaned due to the voltage potential between the cleaningplasma 216 and the second sidewall electrode 140 inducing physicalbombardment (e.g., ion bombardment) of the non-volatile by-product 310.

As illustrated by FIG. 3E, after the non-volatile by-product 310 hasbeen effectively bombarded to remove the non-volatile by-product 310disposed on the second processing chamber sidewall 106, the processinggas 126 and the non-volatile by-product 310 is evacuated out of theprocessing chamber 102 via the processing chamber gas outlet 124. Insome embodiments, during evacuation of the processing gas 126 andnon-volatile by-product 310, the switching element 204 of the first RFpower generator 127 disconnects the RF antenna 121 from the RF signalgenerator 202 of the first RF power generator 127. Further, theswitching element 204 of the second sidewall voltage generator 138switches to connect the second sidewall electrode 140 to ground. In someembodiments, the valve of the processing chamber gas outlet 124 remainsopen after the processing gas 126 has been evacuated to pump down thepressure of the processing chamber 102 for a subsequent process.

As illustrated by FIG. 3F, the non-volatile by-product 310 disposed onthe first processing chamber sidewall 104 is being cleaned from thefirst processing chamber sidewall 104. In some embodiments, the cleaningplasma 216 is formed inside the processing chamber 102 by flowing aprocessing gas 126 into the processing chamber 102 and igniting theplasma via RF signals. In some embodiments, the processing gas 126 maycomprise, for example, oxygen, chlorine, boron, nitrogen, hydrogen, or acombination of the foregoing. For example, the valve of the processinggas inlet 122 may open and allow the processing gas 126 to flow into theprocessing chamber 102. After the processing gas 126 has flowed into theprocessing chamber 102, the switching element 204 of the first RF powergenerator 127 closes the circuit between the RF signal generator 202 ofthe first RF power generator 127 and the RF antenna 121.

Unlike during the etching process depicted in FIG. 3B, the switchingelement 204 of the second RF power generator 132 connects the lowerelectrode 108 to ground in order to protect the electrostatic chuck 110during the cleaning process. Rather, the switching element 204 of thefirst sidewall voltage generator 134 switches such that the firstsidewall electrode 136 is connected to the DC bias voltage generator 206of the first sidewall voltage generator 134. In some embodiments, thefirst sidewall electrode 136 may be connected to the DC bias voltagegenerator 206 for a time period in a range of about 400 seconds to about600 seconds. In other embodiments, the first sidewall electrode 136 maybe connected to the DC bias voltage generator 206 for a time period in arange of about 200 seconds to about 400 seconds. By connecting the firstsidewall electrode 136 to the DC bias voltage generator 206 of the firstsidewall voltage generator 134, the non-volatile by-product 310 disposedon the first processing chamber sidewall 104 is effectively cleaned dueto the voltage potential between the cleaning plasma 216 and the firstsidewall electrode 136 inducing physical bombardment (e.g., ionbombardment) of the non-volatile by-product 310.

As illustrated by FIG. 3G, after the non-volatile by-product 310 hasbeen effectively bombarded to remove the non-volatile by-product 310disposed on the first processing chamber sidewall 104, the processinggas 126 and the non-volatile by-product 310 is evacuated out of theprocessing chamber 102 via the processing chamber gas outlet 124. Insome embodiments, during evacuation of the processing gas 126 andnon-volatile by-product 310, the switching element 204 of the first RFpower generator 127 disconnects the RF antenna 121 from the RF signalgenerator 202 of the first RF power generator 127. Further, theswitching element 204 of the first sidewall voltage generator 134switches to connect the first sidewall electrode 136 to ground. In someembodiments, the valve of the processing chamber gas outlet 124 remainsopen after the processing gas 126 has been evacuated to pump down thepressure of the processing chamber 102 for a subsequent process.

With reference to FIGS. 4A-4B, a series of views of some moreembodiments of a method for removing by-product that has accumulated onsidewalls of a processing chamber is provided.

As illustrated by FIG. 4A, the semiconductor processing system 100comprises a power switching manifold 402. In some embodiments, the powerswitching manifold 402 comprises the second RF power generator 132, thefirst sidewall voltage generator 134, and the second sidewall voltagegenerator 138 and controls their respective switching elements 204. Infurther embodiments, the power switching manifold 402 comprises aplurality of switches configured to switch between a first electricpotential node, a second electric potential node, and/or a RF signalgenerator node, such that the power switching manifold controls the nodeconnections to the lower electrode 108, electrostatic chuck 110, thefirst sidewall electrode 136, and the second sidewall electrode 140. Insome embodiments, the second electric potential is larger than the firstelectric potential. For example, the first electric potential is about 0V and the second electric potential is about negative 600 V.

As further illustrated by FIG. 4A, the non-volatile by-product 310disposed on the first processing chamber sidewall 104 is being cleanedfrom the first processing chamber sidewall 104 at the same time thenon-volatile by-product 310 disposed on the second processing chambersidewall 106 is being cleaned from the second processing chambersidewall 106. Similar to the cleaning process depicted in FIGS. 3D and3F, the power switching manifold 402 switches the switching element 204of the second RF power generator 132 to connect the lower electrode 108to ground in order to protect the electrostatic chuck 110 during thecleaning process. However, unlike the cleaning process depicted in FIGS.3D and 3F, the power switching manifold 402 switches the switchingelements 204 of both the first sidewall voltage generator 134 and thesecond sidewall voltage generator 138 to connect them to theirrespective DC bias voltage generator 206. Accordingly, in someembodiments, the non-volatile by-product 310 disposed on both the firstprocessing chamber sidewall 104 and the second processing chambersidewall 106 can be effectively cleaned at the same time by inducingphysical bombardment (e.g., ion bombardment) of the non-volatileby-product 310.

As illustrated by FIG. 4B, after the non-volatile by-product 310 hasbeen effectively bombarded to remove the non-volatile by-product 310disposed on both the first processing chamber sidewall 104 and thesecond processing chamber sidewall 106, the processing gas 126 and thenon-volatile by-product 310 is evacuated out of the processing chamber102 via the processing chamber gas outlet 124. In some embodiments,during evacuation of the processing gas 126 and non-volatile by-product310, the power switching manifold 402 switches the switching element 204of the first RF power generator 127 to disconnect the RF antenna 121from the RF signal generator 202 of the first RF power generator 127.Further, the power switching manifold 402 switches the switchingelements 204 of both the first sidewall voltage generator 134 and thesecond sidewall voltage generator 138 from their respective firstterminal to their respective second terminal, which connects both thefirst sidewall electrode 136 and the second sidewall electrode 140 toground.

With reference to FIG. 5, a flowchart 500 of some embodiments of themethod for removing by-product that has accumulated on sidewalls of aprocessing chamber is provided. While the disclosed method and othermethods illustrated and/or described herein may be illustrated and/ordescribed herein as a series of acts or events, it will be appreciatedthat the illustrated ordering of such acts or events are not to beinterpreted in a limiting sense. For example, some acts may occur indifferent orders and/or concurrently with other acts or events apartfrom those illustrated and/or described herein. Further, not allillustrated acts may be required to implement one or more aspects orembodiments of the description herein, and one or more of the actsdepicted herein may be carried out in one or more separate acts and/orphases.

At 502, the pressure of a processing chamber that has a workpiecedisposed within is pumped down. An example of act 502 can be seen withreference to previously illustrated FIG. 3A.

At 504, the workpiece disposed within the processing chamber isprocessed, which may result in by-product accumulating on sidewalls ofthe processing chamber. An example of act 504 can be seen with referenceto previously illustrated FIG. 3B.

At 506, the processed workpiece is removed from the processing chamber.An example of act 506 can be seen with reference to previouslyillustrated FIG. 3C.

At 508, the pressure of the processing chamber is pumped down. Anexample of act 508 can be seen with reference to previously illustratedFIG. 3C.

At 510, a cleaning plasma is generated inside the processing chamberfrom a processing gas by applying a radio frequency (RF) signal to a RFantenna. An example of act 510 can be seen with reference to previouslyillustrated FIG. 3D.

At 512, a lower electrode is connected to a first electric potential. Anexample of act 512 can be seen with reference to previously illustratedFIG. 3D.

At 514, a bias voltage having a second electric potential that has agreater magnitude than the first electric potential is applied to asidewall electrode to induce ion bombardment of the by-product disposedon the sidewalls of the processing chamber. An example of act 514 can beseen with reference to previously illustrated FIG. 3D.

At 516, the processing gas and the by-product are evacuated from theprocessing chamber. An example of act 516 can be seen with reference topreviously illustrated FIG. 3E.

Thus, as can be appreciated from above, the present disclosure relatesto an improved method (and related apparatus) for removing by-productthat has accumulated on semiconductor processing chamber sidewalls.

Accordingly, in some embodiments, the present application provides amethod for cleaning a processing chamber. The method includesintroducing a processing a gas into a processing chamber that has aby-product disposed along sidewalls of the processing chamber. A plasmais generated from the processing gas using a radio frequency (RF)signal. A lower electrode is connected to a first electric potential.Concurrently, a bias voltage having a second electric potential isapplied to a sidewall electrode to induce ion bombardment of theby-product, in which the second electric potential has a largermagnitude than the first electric potential. The processing gas is thenevacuated from the processing chamber.

In other embodiments, the present application provides a plasmaprocessing apparatus. The plasma processing apparatus includes aprocessing chamber comprising a lower electrode arranged below an uppersurface of an electrostatic chuck configured to receive a workpiece andbetween sidewalls of the processing chamber. A first radio frequency(RF) power generator is electrically connected to a RF antenna. Asidewall voltage generator is electrically connected to a sidewallelectrode. A second RF power generator is electrically connected to thelower electrode.

In yet other embodiments, the present application provides a method forcleaning a processing chamber. The method includes connecting aswitching element of a sidewall voltage generator to a first electricpotential, thereby connecting a sidewall electrode to the first electricpotential. A switching element of a second radio frequency (RF) powergenerator is switched to a second electric potential, thereby connectinga lower electrode to the second electric potential. A substratecomprising a first material is processed inside a processing chamber, inwhich the process generates by-product comprising the first materialthat adheres to a sidewall of the processing chamber. The processedsubstrate is removed from the processing chamber. A processing gas isintroduced into the processing chamber. The switching element of thesecond RF power generator is switched to the first electric potential,and concurrently the switching element of the sidewall voltage generatoris switched to a third electric potential. A cleaning plasma isgenerated inside the processing chamber by connecting a first RF powergenerator to a RF antenna. The processing gas and the by-product arethen evacuated from the processing chamber.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method for cleaning a processing chamber, themethod comprising: introducing a processing gas into the processingchamber; connecting a lower electrode that is disposed within theprocessing chamber to a first electric potential, wherein anelectrostatic chuck is disposed within the processing chamber, andwherein the electrostatic chuck and the lower electrode are electricallyinsulated from sidewalls of the processing chamber; applying a biasvoltage having a second electric potential to one or more of thesidewalls of the processing chamber, wherein the first electricpotential is ground and the second electric potential has a largermagnitude than the first electric potential; generating a plasma fromthe processing gas inside the processing chamber; and evacuating theprocessing gas from the processing chamber.
 2. The method of claim 1,wherein applying the bias voltage to the one or more of the sidewalls ofthe processing chamber induces ion-bombardment of a contaminationmaterial disposed on the one or more of the sidewalls of the processingchamber.
 3. The method of claim 2, wherein generating the plasmacomprises applying a radio frequency (RF) signal to a RF antenna.
 4. Themethod of claim 1, wherein: an electrostatic chuck pedestal is disposedin the processing chamber; the electrostatic chuck pedestal supportsboth the electrostatic chuck and the lower electrode; and theelectrostatic chuck pedestal vertically separates a lower surface of theprocessing chamber from both the lower electrode and the electrostaticchuck.
 5. The method of claim 1, further comprising: before theprocessing gas is introduced into the processing chamber, etching aworkpiece inside the processing chamber, wherein etching the workpiecedislodges a material from the workpiece that adheres to the one or moreof the sidewalls of the processing chamber; and before the processinggas is introduced into the processing chamber and after the workpiecehas been etched, removing the workpiece from the processing chamber. 6.The method of claim 5, wherein applying the bias voltage to the one ormore of the sidewalls of the processing chamber induces ion-bombardmentof the material.
 7. The method of claim 1, wherein the processing gascomprises chlorine or oxygen.
 8. The method of claim 1, wherein thesecond electric potential is between about negative 0.1 Volts (V) andabout negative 600 V.
 9. A method for cleaning a processing chamber, themethod comprising: connecting a sidewall of the processing chamber to afirst electric potential, wherein the first electric potential isground; connecting a lower electrode that is disposed within theprocessing chamber to a second electric potential, wherein a magnitudeof the second electric potential is greater than a magnitude of thefirst electric potential; while the sidewall of the processing chamberis connected to the first electric potential and the lower electrode isconnected to the second electric potential, processing a workpieceinside the processing chamber, wherein the processing of the workpiececauses a contamination material to adhere to the sidewall of theprocessing chamber; and after the contamination material is adhered tothe sidewall of the processing chamber, performing a cleaning process onthe processing chamber, wherein the cleaning process comprises:connecting the lower electrode to the first electric potential andconnecting the sidewall of the processing chamber to a third electricpotential, wherein a magnitude of the third electric potential isgreater than the magnitude of the first electric potential; introducinga processing gas into the processing chamber; while the lower electrodeis connected to the first electric potential and the sidewall of theprocessing chamber is connected to the third electric potential,generating a cleaning plasma inside the processing chamber that at leastpartially removes the contamination material from the sidewall of theprocessing chamber; and evacuating the processing gas and thecontamination material that was removed by the cleaning plasma from theprocessing chamber.
 10. The method of claim 9, wherein: connecting thesidewall to the third electric potential comprises disconnecting aswitching element of a first sidewall voltage generator from a firstterminal having the first electric potential and connecting theswitching element of the first sidewall voltage generator to a secondterminal having the third electric potential.
 11. The method of claim 9,wherein: connecting the lower electrode to the second electric potentialcomprises connecting a switching element of a first radio frequency (RF)power generator to a third terminal having the second electricpotential; and connecting the lower electrode to the first electricpotential comprises disconnecting the switching element of the first RFpower generator from the third terminal and connecting the switchingelement of the first RF power generator to a fourth terminal having thefirst electric potential.
 12. The method of claim 11, wherein:connecting the sidewall to the third electric potential comprisesdisconnecting a switching element of a first sidewall voltage generatorfrom a first terminal having the first electric potential and connectingthe switching element of the first sidewall voltage generator to asecond terminal having the third electric potential.
 13. The method ofclaim 9, wherein: an electrostatic chuck pedestal is disposed at leastpartially in the processing chamber; the electrostatic chuck pedestalsupports the lower electrode and an electrostatic chuck that is disposedin the processing chamber; and the electrostatic chuck and the lowerelectrode are both electrically insulated from the sidewall of theprocessing chamber.
 14. The method of claim 9, wherein the contaminationmaterial is a metal.
 15. The method of claim 9, wherein generating thecleaning plasma comprises applying a radio frequency (RF) signal to a RFantenna.
 16. The method of claim 15, wherein applying the RF signal tothe RF antenna comprises connecting a switching element of a second RFpower generator to a RF signal generator of the second RF powergenerator.
 17. The method of claim 16, further comprising: after thecleaning plasma at least partially removes the contamination materialfrom the sidewall of the processing chamber, disconnecting the switchingelement of the second RF power generator from the RF signal generator,wherein the switching element of the second RF power generator remainsdisconnected from the RF signal generator while both the processing gasand the contamination material that was removed by the cleaning plasmaare evacuated from the processing chamber.
 18. A method for cleaning aprocessing chamber that has a contamination material disposed on a firstsidewall of the processing chamber and disposed on a second sidewall ofthe processing chamber, the method comprising: removing thecontamination material from the first sidewall by: connecting the firstsidewall to a first electric potential; connecting the second sidewallto a second electric potential, wherein the second electric potential isground, and wherein a magnitude of the first electric potential isgreater than a magnitude of the second electric potential; connecting alower electrode disposed in the processing chamber to the secondelectric potential; generating a first cleaning plasma in the processingchamber, wherein the first cleaning plasma removes the contaminationmaterial from the first sidewall; and evacuating the contaminationmaterial that was removed by the first cleaning plasma from theprocessing chamber; and after the contamination material is removed fromthe first sidewall, removing the contamination material from the secondsidewall by: connecting the first sidewall to the second electricpotential; connecting the second sidewall to a third electric potential,wherein a magnitude of the third electric potential is greater than themagnitude of the second electric potential; applying the second electricpotential to the lower electrode; generating a second cleaning plasma inthe processing chamber, wherein the second cleaning plasma removes thecontamination material from the second sidewall; and evacuating thecontamination material that was removed by the second cleaning plasmafrom the processing chamber.
 19. The method of claim 18, wherein: thefirst cleaning plasma removing the contamination material from the firstsidewall comprises ions of the first cleaning plasma bombarding thecontamination material disposed on the first sidewall; and the secondcleaning plasma removing the contamination material from the secondsidewall comprises ions of the second cleaning plasma bombarding thecontamination material disposed on the second sidewall.
 20. The methodof claim 18, wherein: removing the contamination material from the firstsidewall further comprises flowing a first processing gas into theprocessing chamber; the first cleaning plasma is generated from thefirst processing gas; removing the contamination material from thesecond sidewall further comprises flowing a second processing gas intothe processing chamber; the second cleaning plasma is generated from thesecond processing gas; and a chemical composition of the secondprocessing gas is substantially the same as a chemical composition ofthe first processing gas.